Feeders, which deposit flat objects such as pages, page stacks, glued or bound pages, envelopes, sheets or cards onto collecting or combination lines, are known from the prior art. Such feeders are known from EP 2 548 826 A, EP 0 813 496 B1 and EP 1 591 388 B1, for example. Feeders of this type are used in combination lines for mail pieces that contain supplements. The contents of a mail piece are collected in collection areas of the combination lines and then fed to an enveloping or packaging device, which inserts the contents of the mail piece into an envelope or packages them with a wrapper. The contents of the mail pieces, formed from flat objects, are deposited in the collecting areas of the combination line by one or more such feeders that are arranged along the combination lines. Particularly if the content of the mail pieces consists of different types of objects, e.g. pages of different format or pages and cards, a number of different feeders are positioned in sequence along the combination line, wherein each feeder stores flat objects and deposits them in the defined collection areas. The different objects that are collected in the collecting areas of the combination line and that form the contents of a mail piece are stored in specific feeders, wherein the specific feeders are tailored to the nature or type of the respective objects stored therein. Thus special feeders can be set up for single pages of different formats or for folded or for stapled or glued page stacks or for cards, etc. Depending on the composition of the objects to be processed, the combination line is equipped with appropriate feeders, wherein the feeders can be interchangeably arranged in the combination line.
Additional supplement feeders are known from US 2003/0080490 A and US 2005/0082744 A, for example. These supplement feeders contain a stack compartment for receiving the flat objects in the form of a stack and a takeoff device for taking individual objects off the stack. The takeoff device contains a conveying element, e.g. in the form of a driven belt, and a gate through which the objects taken off of the stack are separately led.
In such supplement feeders, there can be malfunctions, particularly when processing objects with differing thicknesses, for example, by taking two or more objects off the object stack and feeding them simultaneously through the gate. Such malfunctions can occur, for example, if the frictional force between the lowermost objects in the stack of stacked items is greater than the retaining force of the gate. If the tensile force with which the takeoff device takes the lowermost sheets off the stack is not sufficiently large to overcome the retaining force of the gate, it is also possible that no object may be taken off of the stack.
Particularly for processing thicker objects, e.g. folded sheets or envelopes, special gates have therefore been developed for such supplement feeders. For example, such gates have a corrugation device with which the object being led through the gate is deformed in a wave-like manner in order to reduce the surface friction of the object being pulled out of the object stack and to stabilize the flexible object while it is being led through the gate. Such a gate arrangement with a corrugation device is known from U.S. Pat. No. 7,722,028 B2. The gate arrangement comprises a plurality of deflection rollers that are arranged above a conveying device with a plurality of conveyor belts arranged one alongside another, and the rollers are lowered between the side-by-side conveyor belts sufficiently that they impart wave-like protrusions to the object lying on the conveyor belts. The deflection rollers are arranged transverse to the conveyance direction with a distance between one another on a shaft, and this shaft is movable in relation to the surface of the conveyor belts such that the distance between the deflection rollers and the surface of the conveyor belts can be adjusted to a suitable value. The degree of deformations that are imparted to the object can be suitably selected by adjusting the distance between the deflection rollers and the surface of the conveyor belt. Alongside and between the deflection rollers on the shaft, friction rollers are also arranged, which seize the lowermost object in the object stack and clamp it between their outer circumference and the conveyor belts in order to lead the object in the conveying direction through the gate due to the conveyance movement of the conveyor belts. The friction wheels function in this manner as a separating device for the individual objects to be taken off of the object stack. The deflection wheels, which deform the individual objects taken off the object stack in a wave-like shape, act as a support or stabilizer for the object as it is being led through the gate.
Feeders that are equipped with this known gate device can process relatively thick objects well, without distortions of the object appearing during takeoff and separation of the objects that could lead to malfunctions or congestion during continuous takeoff of the objects from the object stack.
The known gate device proves to be disadvantageous, however, if different objects, and particularly objects of different thicknesses, are to be processed with a supplement feeder having such a gate. Problems operating the known gate occur particularly when processing thin objects, because there are often double and multiple takeoffs. To avoid this, the width of the gate gap can be reduced in order to increase the retaining force of the gate. However this can lead to distortions of the conveyed objects or even to damage to the objects. In particular, an excessively strong retaining force of the gate leads to lasting marks on the objects led through the gate, which are imparted to the object due to the wave-like deformations by the deflecting rollers of the gate device. Such lasting marks are very undesirable. In addition, there can be excessively large deformations in thin objects due to the deflection wheels, and therefore damage can occur to the object that can lead to object congestion in the gate.
In order to be able to process thin objects, a different feeder must be used, or at least the gate device must be exchanged. Feeders and gate devices that are suitable for processing thin objects are known, e.g. from the publications US 2003/0080490 A and US 2005/0082744 A mentioned above. However, these cause problems with thicker objects. In the case of folded sheets, for example, the fold may be pulled open in these feeders and thus objects may be damaged and object backups will frequently occur in the gate.
For these reasons, it has so far been necessary to have specially matched or at least suitable feeders for each type of object to be processed. First, this causes a considerable expense for configuration or installation when changing the feeders in a combination line if there is to be a change of objects. Second, this requires stocking multiple different feeders or gate devices, which requires high procurement costs and a number of storage locations because the storage feeders or gate devices are only required for handling certain jobs.